A geode is typically a spherical, geological rock formation with an interior core space containing an inner lining of crystals projecting inward or layers of concentric banding. Geodes are essentially rock cavities or “vugs” with internal crystal formations or concentric banding. The plain geode exterior is generally limestone or a related rock that often reveals nothing of the beautiful, intricate display of interior crystals or banding. Other geodes are completely filled with crystal or solid throughout. These types of solid geodes are called nodules. Geodes can be found all over the world and are most commonly located in deserts, volcanic ash beds, or regions containing limestone. Geodes are commonly found in California, Utah, Arizona, and numerous locations in Mexico, Brazil, and Namibia.
Geodes can be cut open to reveal the crystals in the core of the geode. Quartz is the most common mineral forming crystals within geodes. Still geode cores contain agate, chalcedony, or jasper banding or crystals such as calcite, dolomite, celestite, etc. The color of the crystals depends on the type of contaminant that entered the geode when it was forming. Samples of geodes with unusual colors or highly unlikely formations are either synthetically dyed or altered with artificial colorants or pigments.
There are generally two types of geodes: geodes formed from lava and geodes formed from dolomite, a limestone-like sedimentary rock. Cooling molten lava begins the geode formation process. Cooling lava release gases forming bubbles when gas is trapped within the cooling lava. Trapped bubbles turn into cavities known as thunder eggs once the lava hardens. Minerals, such as quartz, are usually introduced into the thunder egg through a flow of mineral-rich water, thus creating the opportunity for crystals to form within the cavities.
Geodes originating from dolomite start formation when lime sediments develop in warm saltwater. When the saltwater interacts with sediments rich in calcite, the calcite metastasizes into the minerals dolomite and anhydrite. The anhydrite then turns into hard spheroid bodies inside the dolomite, but anhydrite dissolves in a low amount of acid in water. Thus, after acidic water is introduced, outer areas of the anhydrite break away and are replaced with small fibers of crystal quartz. Quartz deposited from mineral-rich waters form crystals within the geode's core. The dolomite then converts from sediment into a hard rock. The center of the anhydrite bodies disperses. Over time the rocks disintegrate, leaving the dolomite to dissolve. The hardened quartz then separated from the dolomite, turning into geodes formed on the ground.
Before opening a geode, it is impossible to know exactly what, if anything is inside. The only way to experience a geode's interior beauty is to open it up. This problematic step often results in crumbled geodes, damage to various tools, and dangerous airborne geode pieces. Much of a geode's beauty is lost when a whole geode crumbles. Geodes can be broken open using a diamond-bladed saw, hammer, hammer and chisel, or rock saw. Diamond-bladed saws are very expensive and dangerous for everyday use. Socks are often used to surround a geode when breaking it with a hammer to prevent bits from flying off into unprotected eyes. It is difficult, however, to accurately break the geode into viable pieces when placing it within a sock and hitting it with a hammer. A pipe cutter can be used to press a rolling carbon blade against a rock to cleanly cut it. Success with pipe cutters and geodes, however, is not guaranteed with every cut. Children, for example, have a very difficult time safely breaking geodes open into salvageable pieces.
Accordingly, there exists a need for an improved means to break, reassemble, and safely re-break a geode to appreciate the beautiful interior core of crystals or concentric banding.